The mechanisms by which cariogenic streptococci interact with teeth, dental plaque components and with each other are being investigated. For Streptococcus mutans adherent and coherent interactions are mediated by insoluble, extra-cellular glucans synthesized from sucrose; the lipoteichoic acids of S. mutans also appear to be involved in adherence. Radioactive and turbidimetric methods have now been developed that accurately and reproducibly measure S. mutans adherence and coherence in growing and in nongrowing bacterial systems. The effects on these processes of antimicrobial agents, chemical agents, enzymes, dental plaque constituents, saliva and changes in ionic environment are being evaluated. BIBLIOGRAPHIC REFERENCES: Ciardi, J.E., Rolla, G., Bowen W.H., and Reilly, J.A. Adsorption of Streptococcus mutans lipoteichoic acid to hydroxyapatite. Scand. J. Dent. Res., In Press, 1977. Ciardi, J.E., Beaman, A.J., and Wittenberger, C.L., Purification, resolution and interaction of the glucosyltransferases of Streptococcus mutans, Strain 6715. Infection and Immunity. In Press. 1977.